Iron with self-cleaning sole plate

ABSTRACT

The invention relates to an iron comprising a sole plate which forms the ironing surface. An oxidation catalyst, which is active on organic dirt, covers the ironing surface. Said catalyst is active when the soleplate reaches a temperature which is at least equal to or higher than 90° C.

[0001] The present invention relates to pressing irons.

[0002] Pressing irons have qualities of ease of use and efficiencydepending inter alia on the state and the nature of the ironing surfaceof their soleplate. Soleplates have been able to be improved by the carebrought to the sliding qualities of the ironing surface, combined withqualities permitting easier spreading out of the laundry. One manner ofobtaining these qualities is to resort to enameled soleplates with anenamel having a smooth appearance, with possibly raised lines permittingspreading of the fabric during displacement of the iron. Other metalsoleplates mechanically treated and/or covered or not with a deposit tofacilitate sliding can equally be suitable for a satisfactory usage.

[0003] However, during use, the soleplate can be tarnished bycarbonizing in a more or less diffuse manner on the ironing surface, andin a more or less incomplete manner, various organic particles trappedby rubbing on the fabrics being ironed.

[0004] But when the soleplate is tarnished even in a manner that ishardly visible, it partially loses its sliding qualities. Imperceptibly,with the soiling, the ironing becomes more difficult. Moreover, the userbecomes apprehensive of using a tarnished iron, fearing that it canalter the laundry.

[0005] Pressing iron soleplate coatings are known that have a hard anddurable layer covered, as indicated by the patent U.S. Pat. No.4,862,609, by a layer improving its surface properties. But this patentdoes not indicate a solution for combating soiling.

[0006] The object of the invention described herebelow is aself-cleaning pressing iron, the soleplate of which is maintained cleanof any contamination by organic particles and is not clogged by normalusage, in a manner to retain its initial qualities.

[0007] The goal of the invention is achieved by a pressing iron having asoleplate, the outer surface of which comprises the ironing surface,characterized in that an oxidation catalyst having an oxidationcatalytic agent is present or distributed in and/or on a surface layerof said soleplate, said oxidation catalyst being active with respect toorganic dirt at a temperature at least equal to 90° C.

[0008] Due to the invention, during ironing, organic particles capturedby the soleplate are oxidized. They are to some extent burned when thepressing iron is hot, the possible solid residue loses all adherence andis detached from the soleplate. The soleplate is maintained clean.

[0009] In fields very different from ironing, an oxidation catalyst hasalready been associated with an external surface of a support.

[0010] Enameled self-cleaning surfaces are known, for example in ovensand cooking utensils such as described for example in the patent U.S.Pat. No. 4,029,603 or the patent FR 2400876.

[0011] The patent U.S. Pat. No. 4,994,430 describes an enameled coatinghaving a dense layer and at the surface a porous layer supporting acatalyst. But such a thick, porous layer is incompatible with ironing.

[0012] There is also known from the patent U.S. Pat. No. 5,388,177 adeodorizing heating element, the enameled surface of which is coatedwith a catalyst, but the catalyst is provided only for deodorizing.

[0013] In any case, the solutions described in these documents cannot beapplied to a pressing iron, since one could fear in particular that, onthe one hand the requirements of low roughness for the ironing surfaceare opposed to the retention of the oxidation catalyst, and on the otherhand the rubbing resulting from the ironing rapidly removes theoxidation catalyst from the external surface of the ironing soleplate.

[0014] The oxidation catalyst is distributed on and/or in the surfacelayer of the iron, where it is in contact with the dirt, or stains.

[0015] In practice, the oxidation catalyst is present and/or distributedon the surface over all or part of the outer surface of the soleplate.

[0016] Thus, the oxidation catalyst can be present or distributedbetween predetermined zones of the outer surface of the soleplate, forexample in the recessed zones of the outer surface, susceptible tocapturing or accumulating dirt and in general hotter than the ironingsurface, which is favorable for oxidation or catalytic.

[0017] When the outer surface of the soleplate has one or several partsthat are recessed with respect to the remaining flat part, forming theuseful surface or the ironing surface proper, the oxidation catalyst ispresent or distributed in the recessed part or parts, to the exclusionof the ironing surface.

[0018] But, of course, the oxidation catalyst can be present, over allor part of the ironing surface proper.

[0019] The catalytic oxidation agent considered according to the presentinvention is thus any element, compound or composition capable ofoxidizing, at a temperature at least equal to 90° C., any organicsubstance such as contained in the dirt, or stains, presentlyencountered in the treatment (including washing and possibly softening)of textile articles or pieces (for example linen).

[0020] Such a catalytic oxidation agent can be specific or non-specificfor one organic substance or another.

[0021] In practice, the oxidation catalyst can have or not, in additionto the catalytic oxidation agent, an inert support, for example individed or particle form, for example alumina, at the surface (includinginternally) of which the catalytic oxidation agent is distributed ordispersed. The inert support can itself constitute, in the non-dividedstate, the surface layer that will be discussed herebelow.

[0022] As examples of catalytically active elements, one can citepalladium, platinum, vanadium, copper or any composition of suchcatalytically active elements (in terms of oxidation). In the activecatalytic compositions considered according to the present invention,there can be present oxides of copper, manganese or cobalt, increasingthe catalytic effectiveness or the stability of the catalytic agent.

[0023] In practice, such oxidation catalysts are well known per se, aswell as the processes for obtaining them, without there being a need todescribe them by the details of their methods of preparationrespectively. Thus, by way of example, in the matter of platinum as acatalytic oxidation agent, its catalytically active form can be obtainedby calcination or decomposition of a chloro-platinic acid salt or anyother precursor.

[0024] Of course, any oxidation catalyst retained according to thepresent invention should remain sufficiently stable at the workingtemperature of the ironing surface, and this within the limits of theuseful life of the pressing iron.

[0025] In practice, the oxidation catalyst according to the invention isfound distributed at least in and/or on the surface layer of thesoleplate of the pressing iron. By “surface layer”, there is intendedany limiting layer, of which the thickness can, by way of example, be atleast equal to 500 nanometers and particularly comprised between 20nanometers and 120 nanometers in contact at one side with another layeror the substrate of the soleplate and providing at the other side aninterface with the outside, having the ironing surface proper. Theoxidation catalyst or the catalytic oxidation agent can be distributedover all or part of the outer surface of the soleplate, in the thicknessand/or on the above-cited outer layer, in a continuous or discontinuousmanner.

[0026] By “ironing surface”, there is intended all or the useful part ofthe outer surface of the soleplate, coming directly in contact with thelaundry during ironing.

[0027] When the oxidation catalyst remains on the surface layer of thesoleplate, it can form a layer or a film that is continuous ordiscontinuous.

[0028] The above-cited surface layer cannot be distinguished from therest of the soleplate, of its substrate, or of a constituent layer ofthis latter, in which case, in the present description and in thefollowing claims, use of the term “surface layer” only has the object ofdistinguishing the limited thickness, possibly zero, of the soleplate,in which the oxidation catalyst or the catalytic oxidation agent can bedistributed and incorporated.

[0029] The thickness of the surface layer in which the catalyst orcatalytic oxidation layer can be comprised depends particularly on thedepth of migration of organic dirt into the interior of the soleplate ofthe pressing iron, starting from the outer surface.

[0030] By “organic dirt”, there is intended any substance that iscombustible or oxidizable on contact with ambient air, completely orpartially. By way of example, one can cite any residue of syntheticfibers, such as used in textile articles, for example in organicpolymers such as polyamide or polyester or any residue of washingproducts or possibly of softening products.

[0031] By of example, the catalytic oxidation agent comprises a metal ofgroup IV of the periodic table or a noble metal, for example palladiumand/or vanadium.

[0032] The oxidation catalyst being active at a soleplate temperaturegreater than or equal to 90° C., it cleans said soleplate when it ishot.

[0033] In a first mode of operation, the catalyst acts at the ironingtemperature of the iron, and the soleplate is maintained cleanpermanently to the extent that the iron is used for ironing.

[0034] In a second mode of operation, during a phase calledself-cleaning, before or after use of the pressing iron, the iron isregulated to an elevated temperature equal to or greater than thehighest ironing temperatures. It is then left alone during apredetermined time, during which the oxidation catalyst produces itseffect. The user can thus maintain the iron regularly, without awaitinga harmful soiling.

[0035] In a first version, the iron has a metal soleplate clad with anenamel having a low porosity and/or roughness at the micrometric and/ornanometric scale, and the oxidation catalyst belongs to the surfacelayer of the enamel cladding. The enamel is, for example, a vitrifiedenamel.

[0036] Such an enamel is chosen from among the enamels having a lowporosity, for example vitrified, known for their ironing qualities, thisin comparison with the enamels used in ovens or on grills, which beingporous require needlessly the deposit of a substantial quantity ofoxidation catalyst and do not have the qualities required for asoleplate of a pressing iron.

[0037] The enamel should in effect at least be hard, have good slidingproperty and resist the penetration of steam or warm moisture.

[0038] The attainment or the application of the oxidation catalyst or ofthe catalytic oxidation agent on or in the above-cited surface layer canbe performed by any known means such as by the application of anyprecursor of the catalytic oxidation agent, then baking by using apyrolytic process or by electrophoresis or by chemical depositionwithout current called “electroless” or by vapor deposition.

[0039] By “precursor”, there is intended any chemical orphysico-chemical form of the oxidation catalyst and/or of the catalyticoxidation agent which is capable of ending with or liberating thislatter by any appropriate treatment, for example pyrolysis. By way ofexample, any chloro-platinic acid salt is a precursor for the platinumconsidered as an oxidation catalyst.

[0040] As shown by the examples herebelow, the choice of the compositionof the oxidation catalyst or of the catalytic oxidation agent, and/orthe condition of obtaining or application of this latter are determinedto not substantially alter the intrinsic qualities of the ironingsurface, notably its glide.

[0041] In a second version, the pressing iron has a metal soleplate, forexample an aluminum alloy, and a surface layer is added to the outersurface of said soleplate, in the form of a thin layer of a support, forexample alumina, for said agent for catalytic oxidation of said organicdirt.

[0042] By way of variation, the soleplate is clad with a layer of apolymer resistant to all oxidation at high temperature, for examplepolytetrafluoroethylene, and the surface layer belongs to said polymerlayer.

[0043] In a third version, the surface layer consists of a thin layer ofthe oxidation catalyst, comprising an inert support, for examplealumina, and a catalytic oxidation agent supported by said support.

[0044] In a general manner, the invention also concerns the use of anoxidation catalyst as a self-cleaning agent for all or part of the outersurface of the soleplate of a pressing iron.

[0045] The invention will be better understood from a reading of thefollowing examples and the attached drawings.

[0046]FIG. 1 is a cross-sectional view of a soleplate of a pressing ironaccording to the invention.

[0047]FIG. 2 is a bottom view of a pressing iron according to theinvention, showing the lower face of the soleplate.

EXAMPLE 1

[0048] In a first example of realization, pressing iron 1 visible inFIG. 1 has a soleplate 2 of aluminum fixed to a heating base 3 of moldedaluminum and furnished with a heating element 4. Soleplate 2 is coatedon its external surface 5 more easily visible in FIG. 2 by an enamelknown for its ironing qualities. The catalyst or catalytic oxidationagent is deposited in a very thin layer on the outer surface. This outersurface 5 has the ironing surface 51 proper, and recessed parts 52, 53for example around steam outlet orifices 6.

[0049] For this purpose, the outer surface is degreased and activated bya light acid attack, for example with a citric or nitric acid solution.A precursor of the catalytic oxidation agent is prepared, for example bydissolving palladium nitrate in water at a rate of 2 grams of palladiumnitrate per liter. Moreover, several companies, for example the companyPCAS of Longjumeau, France, furnish more developed precursors. Thesoleplate being heated to around 300° C., the precursor is applied insolution on the soleplate by allowing it to pass below an ultrasonicatomizer, in one or several passes, to obtain a good homogeneity of theapplication. The assembly is baked at around 300° C. The thickness ofthe layer of oxidation catalyst (palladium) thus obtained can vary from20 to 120 nanometers. Preferably, the device is regulated to obtain athickness of the order of 30 nanometers. One notes that the deposit ofpalladium is adherent to the ironing surface, and does not disturb theglide characteristics of the underlying enamel in a noticeable manner.

[0050] The effectiveness of the oxidation catalyst can be measured in aclosed enclosure. A sample of the soleplate is heated to 300° C., onwhich is deposited a piece of fiber, of organic polymer, of 2 mg, meltedrepresentative of dirt. After having dosed the initial quantity ofcarbonic gas into the enclosure, one notes its increase, attesting tothe effectiveness of this solution.

[0051] In the example thus described, there was obtained a catalyticactivity at 300 degrees having permitted production of 107×10⁻⁶ moles ofcarbonic gas per hour, for a catalytically surface, sample, of 10 squarecentimeters.

EXAMPLE 2

[0052] In a second example of realization, the enameled soleplate isheated to 300 degrees. A solution comprising alumina in suspension isprepared by mixing 4 grams of tetraethylorthosilicate with 96 grams ofnitric acid diluted to 0.6%, to which is added 12.8 grams of “DISPERSALS”. This latter alumina based product is furnished by the companyCONDEA. The solution diluted 10 times is sprayed on the soleplate. Thesoleplate is maintained at 300 degrees during one hour. The spraying isregulated to obtain a deposit in solid form of around 10 micrometersthickness, of a support of catalytic oxidation agent that is aluminabased. Then an aqueous solution of palladium nitrate is sprayed, whichis subjected to baking at 300 degrees for one hour.

[0053] With respect to the preceding example, the activity of a sameactive catalytic surface, sample, is brought to 175×10⁻⁶ moles ofcarbonic gas produced per hour.

EXAMPLE 3

[0054] In a third example of realization, the iron has an aluminumsoleplate. The ironing surface is cleaned by a sodic attack followed bya neutralization and a rinsing. The soleplate is oxidized in an oven at560 degrees for 30 minutes, then there is applied by spraying a solutionof palladium nitrate at 2 grams per liter. After baking at 300 degreesfor one hour, one obtains a catalytically active or oxidation catalystsurface layer of around 30 nanometers thickness.

[0055] One obtains glide properties substantially similar to those ofaluminum. The value of this realization resides in the economy offabrication. The activity obtained is of the order of 112×10⁻⁶ moles ofcarbonic gas produced per hour, for a catalytically active surface,sample, of 10 square centimeters.

[0056] In a variant of this example of realization, the catalyticoxidation agent is incorporated in a surface layer of the Ormosil type,serving as a support, this term being an abbreviation for the Englishexpression “Organically Modified Silicates”, as explained in the article“Structures and properties of Ormosils” of the Journal Sol-Gel Scienceand Technology, 2, 81-86, (1994), written by John D. Mackenzie.Preferably, the surface layer is obtained starting from a liquidsolution intended to produce a gel.

[0057] The catalytic oxidation agent is then deposited on and/or in thissurface layer, by a process similar to the preceding utilizing anultrasonic atomizer. One to four passes permit obtaining a goodhomogeneity. The assembly is then dried, then baked at around 300° C.

EXAMPLE 4

[0058] In a fourth example of realization, the iron has a stainlesssteel soleplate. The ironing surface is cleaned then passivated in a 20%nitric acid bath. On the ironing surface heated to 300 degrees, there isapplied an alumina-based solution such as described in the secondrealization and the soleplate is maintained at 300 degrees for one hourin order to obtain a surface layer serving as a support for thecatalytic oxidation agent. A catalytic oxidation agent layer is thendeposited in and on this surface layer, by spraying with an ultrasonicatomizer a solution of palladium nitrate. The assembly is then driedthen baked at around 300° C. There is measured an effectiveness at 300degrees of 151×10⁻⁶ moles of carbonic gas produced per hour, for acatalytically active surface, sample, of 10 square centimeters.

[0059] In a practical manner, one notes a substantial difference ofsoiling between two irons, only one of which is provided with a selfcleaning soleplate according to the invention.

[0060] It is also noted that when a soiling is thick, it is consumed inthe zone of contact of the oxidation catalyst, then separates from thesoleplate. Self-cleaning is obtained without awaiting completetransformation of the dirt.

[0061] Although the activity of the oxidation catalyst is manifested atthe low temperatures of ironing, however greater than 90° C., thisactivity is much greater at higher temperatures. The user uses thepressing iron in the usual manner. After an ironing session, if there isneed, she acts on a cleaning control button. This control modifies theassigned temperature of the iron, to bring it to a temperaturerecommended for functioning of the oxidation catalyst, and marks thestart of a predetermined self-cleaning phase, during which thistemperature is maintained, and beyond which the heating of the ironhalts automatically. During this phase, the oxidation catalyst exertsits full effect. Dirt that can be adhered to the soleplate is consumedwithout danger, this including in the zones of recesses 52, 53, afterwhich the iron recovers all of its initial properties.

1. Pressing iron having a soleplate, the outer surface of whichcomprises the ironing surface, characterized in that an oxidationcatalyst having an oxidation catalytic agent is present or distributedin and/or on a surface layer of said soleplate, said oxidation catalystbeing active with respect to organic dirt at a temperature at leastequal to 90° C.
 2. Pressing iron according to claim 1, characterized inthat the soleplate is of metal and clad with a layer of enamel having alow porosity, for example vitrified, and the surface layer belongs tosaid layer of enamel.
 3. Pressing iron according to claim 1,characterized in that the soleplate is clad with a layer of a polymerresistant to all oxidation at high temperature, for examplepolytetrafluoroethylene, and the surface layer belongs to said layer ofpolymer.
 4. Pressing iron according to claim 1, characterized in thatthe soleplate is of metal, and the surface layer is added to the outersurface of said soleplate, in the form of a thin layer of a support, forexample alumina, for said agent for catalytic oxidation of said organicdirt.
 5. Pressing iron according to claim 1, characterized in that thecatalytic oxidation agent comprises a metal of group IV of the periodictable or a noble metal, for example palladium and/or vanadium. 6.Pressing iron according to claim 1 characterized in that the surfacelayer consists of a thin layer of the oxidation catalyst, comprising aninert support, for example alumina, and a catalytic oxidation agentsupported by said support.
 7. Pressing iron according to claim 1,according to which the outer surface has at least one part that isrecessed with respect to the remaining flat part, forming the useful orironing surface, characterized in that the oxidation catalyst is presentor distributed in said recessed part, to the exclusion of the ironingsurface.
 8. Pressing iron according to claim 1, characterized in thatthe oxidation catalyst is present and distributed between predeterminedzones of the outer surface of the soleplate, for example recessed zonesof the outer surface, susceptible to capturing or accumulating saiddirt.
 9. Use of an oxidation catalyst as a self-cleaning agent of all orpart of the outer surface of the soleplate of a pressing iron.